Air circuit breaker



March 31, 1953 A. R. MILL-ER 2,633,518

AIR CIRCUIT BREAKER Original Filed July 1, 1948 2 SHEETS-SHEET 1 fi a 35 MarEHBi, 195 3 A. R. MILLER AIR CIRCUIT BREAKER 2 SI-1EETSSHEET 2 Original Filed July 1, 1948 .M N. mi me Marry/Evil Patented Mar. 31, 1953 AIR CIRCUIT BREAKER Archie R. Miller, Easton, Pa., assignor, by mesne assignments, to Roller-Smith Corporation, Bethlehem, Pa., a corporation of New Jersey Original application July 1, 1948, Serial No. 36,309. Dividedand this application August 2, 19.49, SerialNo. 108,150

3' Claims; 1

This invention relates to air circuit breakers particularly applicable to theinterruption of alternating currents and. further relates to a method and'provision of means for extinguishing the arc and for cooling and condensing the vapors and gases.

This application is a division of'my co-pending application Serial No. 36,309, filed July 1, 1948, and relates particularly to the method and provision of means receiving the attenuated arc and dissipating it andfor'cooling and condens ingthe vapors or-gases'and'thereby avoiding any material discharge of'vapors or gases to the outside atmosphere. The disclosures hereof which arenot claimed herein are included and claimed in my said original application.

One object is-to reduce the size of the breaker and the required space for mounting for any given capacity. Owing to the fact that there is no appreciable discharge ofvapors or gases from thebreakers, they may be mounted closely together, especially in stacking one above the other. Also, this freedom from discharge of vapors or gases avoids the necessity of enclosing the-breakers within cubicles and thereby eliminates such additional expense and required space therefor.

Another object is to avoid the use and cost of blow-out magnets and the space required by them. Another object is to control the movement of the arc in such a manner that when the contact surfaces are separated they are relieved from any objectionable arcing effects and the space between them upon separation is cooled and any restriking of the arc is avoided. Another object is to provide a comparatively simple form of structure which may be easily assembled and which-will'permit convenient accessibility to all parts and permit separate removal of the quencher and condenser plates-and access to the parts of the switch between which the arc is drawn. Other objects and advantages will be understood from the following description and accompanying drawings which illustrate a preferred embodiment of the invention.

Fig. 1 is a vertical section of the breaker in a plane perpendicular to the supporting panel; and Fig. 2is' a. front elevation showing the interior of the upper portion of the breaker, the front cover plate being'removed. Fig. 1 shows a form of mechanism for actuating the breaker to closed positionand for releasing it but as this forms no part of the present invention and as any suitable mechanism may be used, it will be described only generally. A

' supporting panel I of insulating material is shown at theleft of Fig, 1'. A U-shaped frame-2 is fixedto the support and between its two out wardly extending arms is pivotally mounted a square shaft 3. Two upwardly extending side plates 4 are mounted on the shaft 3 and insulated therefrom. These side plates are actuated to the closed position of the breaker shown in Fig. 1 by a toggle mechanism comprising a lever 5 pivotally mounted between the arms of the-frame 2. The inner end of. the lever 5 is pivotally connected to a link 5 which in turn is pivotally connected to another link 1, the inner end of which is pivotally connected to the side plates 4, Another'link 8 is pivotally connected to the connection between the links 6 and l and has its lower end pivotally connected to a lever 9. This lever is pivoted at its upper end between the arms of the frame 2 and is restrained at its lower end by a latch l0 pivotally mounted between the arms of the frame. When this latch. is tripped automatically by responsive means. not shown, the breaker moves to its open position, or it may be opened manually by actuation of the latch shaft.

Mounted between the breaker side plates 4 is a copper block H having an inner contact surface which, when the breaker is closed; engages a main forwardly spring pressed contact element [2 pivotally mounted on and electrically connected to a main conductor or bar 1 3 passing through and supported on thepanel i. A flexible copper conductor M is clamped at its upper end to the block I i and secured at its lower inner end to a conducting copper block i5 fixed to the panel and in electrical connection with the other main conductor or bar H5 passing rearwardly through the panel.

The side plates 4 of the breaker are bent toward each other above their middle portions and then, as shown in Fig. 2, extend upward parallel to each other. in much closer relationship than the lower portions. Between the upper ends of the side plates is pivotally supported a block ll, as shown in Fig, 1, of cold rolled steel. This supports the movable arc contact element 18 of the breaker. This element is a copper strap, the upper end of which curves around the rounded upper end of the block 17, then down along its rear face, is then bent at right-angles to pass under the lower end of the block and is then bent again at right-angles to extend downwardly therefrom. It is secured to the block by screws 13a. The contact element It is faced on its rear surface by a contact I82) of suitable arc resisting material such as a composition of silver or copii per tungsten, r other suitable materials. A copper strap I9 is secured and soldered at its upper end to the lower end of the secondary contact element l3 and its lower end is in electrical connection with the flexible conductor M by being soldered thereto and clamped by a block Ma. The contact element i8 is spring pressed inwardly on the pivot of the block if.

When the breaker opens, the main contact is opened first between the block Ii and the conductor l2 and then the auxiliary contact itb separates from the fixed auxiliary contact and in this movement the block i? and element I8 swing rearwardly on their pivot to maintain con nection with the secondary fixed contact until the breaker is in a position to transfer the arc to the arc runners. In closing the breaker, the secondary contacts first engage and then the main contacts engage.

The means for extinguishin and quenching the arc and for absorbing the vapors and gases are enclosed by the panel at the rear, 2. front cover plate 29, side cover plates Eta and 25b and a top cover plate 260, these plates being of insulating material. The enclosure is open at the bottom.

Referring to Fig. 1, the main conductor is is supported by an angle iron 2! at the back of the panel and one of its bolts Zia extends through the panel and engages a cold rolled steel block 22 on the front of the panel. The stationary secondary contact element is in the form of a copper bar or strap 23 having a contact 230. of suitable aro resisting metal which faces the movable contact 18a. The contact element 23 is inclined rearwardly toward the panel and then extends upwardly to form a runner for the arc. This element is secured to and is backed along most of its length by a supporting bar 24 of hard copper. The lower end of this bar is supported on the main conductor it and secured thereto by a screw bolt 2411 which also passes rearwardly through the lower end portion of the contact element 23. The bar 24 is backed by a cold rolled steel plate 25 which is secured thereto by screws 25a. In front of the lower end of the bar 2 3 and below the lower end of the conducting strip 23 an angular bracket 26 of insulating material is fixed to the bar 2G to serve as a shield.

The inclined front face of the steel block 22 serves to support the back of the steel plate 25. The top of the steel block is covered by a small plate 2! of insulating material. Above this and secured to the panel by the bolts 28a. is a cold rolled steel plate 23. This extends upwardly opposite and near the back of the stationary conducting element or runner 23 and also some distance beyond its upper end and is about twice the width of the runner 23, thus extending sidewise beyond both edges of the runner. It is faced by a thin sheet 29 of insulating material such as asbestos lumber.

Secured to opposite sides of the steel back plate 28 by screw bolts ilta are cold rolled steel plates 3B. These plates are shown in Fig. 1 as of rectangular form and extend forwardly at opposite sides of the arc runner The inside faces of these plates are lined by sheets Iii of insulating material, such as asbestos lumber, and are se cured at the rear by the screws fits. These sheets extend forwardly to the front cover 2%. They are faced on their inside upper portions on opposite sides of the arcing region by insulating plates 32 of asbestos lumber and are held in place by the bolts Sta. The two sets of plates 30, 3|

and 32 are respectively clamped together by additional bolts 32a. These plates 32 are shown in 2 as having tapered lower edges. On the outside of each of the steel plates 3f] is another sheet 33 of insulating material of asbestos lumber which extends from the panel to the front cover plate and from below the steel plates st to some distance above them and serve a purpose later explained. They are supported by the upper screw bolts 39a which also pass through the plates 38, sheets at and the plates 32.

On the inside of the front cover plate 29 and supported thereby by the screw bolts 34a is a cold rolled steel plate 35 forming the front plate of the arcing region and of the same size as the rear steel plate 28. The inner face of the plate 34 is lined with a sheet 3'5 of insulating asbestos lumber. A strap 36 of hard copper bent at right-angles is mounted on the inside of the sheet 3d, the bolts 34a serving to hold it in place. The lower leg of the strap 35 extends rearwardly. A strap 3! of hard copper is fixed by screws 37a to the lower side of the strap 33. The strap 31. extends rearwardly toward and just above the path of movement of the conductor is of the breaker and then turns and extends forwardly and upwardly at an angle of about 45 to form the front are runner. The other portion of the strap 3? extends forwardly through an opening in the insulating sheet 25 and through an open-, in 34? in the steel plate 3 and through a similar opening in the front cover 2%, and then is bent at right-angles to extend. downwardly some dis: tance in front of the breaker. A detachable flex; ible lead tlb extends from the lower end of 31'. and is in electrical connection with conductor l4 and clamped in place by the clamping block I la. On the under side of the inclined portion of the strap 31 is secured by the screw 3811 a cold rolled steel bar or plate 38 of considerable thickness.

A cold rolled steel plate 39 is secured by screws to each vertically extending end of the plate 34 and extends rearwardly about halfway of the breaker to embrace the arcing region. The inner edge of these plates is inclined as shown in Fig. l; and these plates are interposed between and covered on their opposite sides by the insulating sheets 3| and 33 already described. They are clamped together by additional bolts 39a. A rectangular plate it of insulating material extends across the top of the plate 34 and sheet 35, as shown in Fig. l.

The form of structure of the cooling and condensing plates and their relationship to other parts will now be described. The side plates 33 extend above the arcing region and have a series of upwardly extending teeth 33b extending along their upper edges and serve as positioning and spacing means for the cooling and condensing plates 4|. These plates are of hard copper and have a large surface area occupying the full width of the upper portion of the casing and considerably beyond the width of the arcing region and have downwardly extending leg portions Mb within the space between the side covers 20a and 20b and the insulating sheets 33. The vapors and gases resulting from the arcing thus have a path from the arcing region up between the plates 4! then sidewise and then down in two paths through the spaces between the legs Mb. The plates 4! are held in spaced position at their upper end corners by bars 42 of insulating material. These bars are notched on their lower sides to engage and space the plates. The bars are supported from the top cover c by'the-screws 42a; and are also engaged'by certain upper screw of the side cover plates and of the front cover plate. A support plate 43 of insulating material for the rear end of the top cover is secured to the panel by the bolts 43a and is engaged by the screws 43b which pass through the top cover. It is also engaged by the screws 43c passing through the side covers. Spacing strips 44 of insulating material are-introduced between the top:portions of the insulating sheets 3| and 23 and extend from the front cover 20 -to the panel. The lower front corners of these strips are notched to rest on the insulating strip 40. The rear ends of the strips pass through slots in the lower portion of the rear plate 43 and rest on top of the lower rear plate 28. At the lower front corners of the side cover plates are corner blocks 45 of fibre engaged by screws which fasten the lower corners of the front cover and side covers together.

In opening the breaker and when the arc is drawn between the arcing contact surfaces l-Bb and 23a as already described, the top portion of the conducting element l8 has then passed close to the inner end of the arc runner 31. In the meantime the alternating current has in duced magnetic fields in the sheet steel enveloping plates 25, 28 and 30 and in the steel block I! which drives the arc upwardly and along the arc runners 23 and 3. As the arc lengthens it is forced upwardly and transferred to between the arc runners 23 and 31. The current then continues to induce magnetic fields in the embracing plates 28 and 30 and also induces currents in the embracing plate 34 and side plates 39 and in the plate 33, the current passing around the latter plate to the shunt connection 3! and thence to the conductor 14. The structure as disclosed permits the travel of the arc to be fast enough to avoid excessive heating or melting of the conducting parts and slow enough to permit the current to approach its zero value in its current cycle by the time it has reached the upper ends of the arc runners and thereby accomplish the extinguishment or the are within the enclosed arcing space. This space embracing the are by the iron or steel plates cannot be too wide as the induced magnetic fields would be too weak to efiectively react on the arc to drive it upwardly; also it is desirable to have the side walls close enough to aid in extinguishment by their cooling efiect.

The cooling and condensing plates 4! are close to the top of the arcing region and aiTord a much wider path than that of the arcing region. This permits the heated gases and vapors to pass from the arcing region to within the spaces between the condensing plates where they are cooled and condensed. Also the vapors and gases are afiorded a long length of travel between these plates upwardly and then downwardly between their depending legs. The vapors and gases are thereby effectively cooled and condensed, with the result that there is no material discharge thereof from the bottom opening of the enclosures.

Convenient accessibility to the interior of the breaker is afforded by permitting the enclosing casing and parts carried thereby and the cooling and condensing plates to be removed as a unit. This is accomplished by removing the bolts 28a and 43a from the back of the panel which then allows the unit to be raised from the other parts of the breaker. The unit may then be readily inspected and further dismantled if necessary.

Likewise thezmovable parts of the breaker; and: stationary contact parts are. fully exposedfor inspection upon the removal. of the. unit. H de sired the enclosing casing may be made sepa-: rately removablefrom the-cooling andicondensing plates.

It is thus apparent that this improvement has various important advantages such assimplicity.

of structure, compactness and small size, efiec tive extinguishment of the arc, cooling and condensing or the vapors and gases with no outward appreciable discharge thereof and durability under long continued use. It also permits the stacking of the breakers in close proximity to each other sidewise as well as one above the other; and that, together with their small size, reduces the space required in their switchgear assemblies. Although the cooling and condensing plates have been described of hardened copper, they may be of other non-magnetic metal, or of insulating material, of a character to withstand the heat and to provide proper cooling efiect, but hardened copper has been found a preferable material for this purpose.

A single pole breaker has been described for simplicity but it is apparent that the improvement may be applied to any number of poles adapted for simultaneous operation or control.

Although a particular embodiment of the invention has been shown and described, it will be understood that it is subject to various modifications according to particular requirements and to the preference of the designer without departing from the scope of the invention.

I claim:

1. An air circuit breaker comprising an enclosure for the arcing region including enclosure plates extending along the sides of the arcing region, the enclosure being open at the top and bottom, a series of cooling plates spaced from each other, extending over the top of the arcing region and extending sidewise in both directions beyond the width of the enclosed arcing region and having downwardly extending legs on the outside of the enclosure plates, and a second enclosure over the top and sides of the cooling plates including the downwardly extending legs for directing the pasage of vapors and gases between such cooling plates and downwardly between the legs, the second enclosure being open below the legs.

2. An air circuit breaker comprising an enclosure for the arcing region including enclosure plates at the sides of the arcing region, the enclosure being open at the top and bottom, a series of cooling plates spaced from each other extending over the top of the arcing region and extending sidewise in one direction beyond one of the enclosure plates and beyond the enclosed arcing region and having downwardly extending legs on one side on the outside of one of the enclosure plates and on the outside of the enclosed arcing region, and a second enclosure extending over the cooling plates and down the outside of the legs for directing the passage of vapors and gases between the cooling plates and then downwardly between the legs, the second enclosure being open at the bottom below the legs.

3. An air circuit breaker comprising an enclosure for the arcing region including enclosure plates at the sides thereof, the enclosure being open at the top and bottom, a series of non-magnetic metal cooling plates spaced from each other, extending over the top of the arcing region and extending beyond the enclosure plates in both directions and having downwardly extending legs REFERENCES CITED v on the outside of the enclosure plates and on The following references are of record in the outside of the enclosed arcing region, and a me of this patent: second enclosure extending over the top of the T m cooling plates and down the outsides of the legs UNITED SiATES TENTS 'fondirecting the passage of vapors and gases bea Numb r Name Date tween the cooling plates and then downwardly 1,904,463 Hilliard Apr. 18, 1933 between the legs, the second enclosure being open 2,293,452 Boehne A 18, 1942 at the bottom beneath the legs. 2,293,513 Linde Aug. 18, 1942 10 2,408,352 Titus Sept. 24,-1946 ARCHIE MILLER- 2,416,164 Ellis et a1. Feb. 18, 1947 2,468,422 Wood Apr. 26, 1949 

